The present invention relates to medical devices for delivering endoprostheses to predetermined treatment sites within body cavities or lumens, and further deploying the endoprostheses at the selected sites. More particularly, this invention relates to such devices that are capable of enabling or facilitating a tracking of the endoprostheses during deployment.
A variety of patient treatment and diagnostic procedures involve the use of prostheses inserted into the body of a patient and intraluminally implanted. Percutaneous translumenal coronary angioplasty (PTCA) and other vascular treatments frequently involve implanting prostheses such as stents to maintain vessel patency or grafts to shunt blood. Similar implantations are used in non-vascular procedures, e.g., enteral, billiary, and esophageal applications.
There is a need to accurately characterize the intended implant site to facilitate proper placement of the prosthesis. There is a further need, just before deployment and during deployment, to ascertain the location of the prosthesis relative to the intended placement site. One known approach to such characterizing and monitoring is angiography, which involves supplying a radiopaque contrast fluid to the cavity or lumen, then radiographically viewing the lumen. This approach, however, provides only a monochromatic, two-dimensional image showing a profile but no depth of field.
According to another approach, radiopaque markers can be placed on the delivery/deployment device. Before deployment, the position of the prosthesis within the device is known, and determining the device position in effect accurately determines the prosthesis position. This advantage is lost during deployment, however, and again the image offers neither distinctions in color nor depth of field.
According to yet another approach, the prosthesis can be fabricated at least in part using a radiopaque material. For example, the filaments of a stent can be formed of, or may incorporate a core formed of, platinum, tantalum or another radiopaque material. This approach likewise lacks the capacity for distinction among colors, and imposes limitations upon the materials used to form the prosthesis.
U.S. Pat. No. 5,411,016 discloses an intravascular balloon catheter having a lumen containing an angioscope. A distal portion of the catheter shaft, surrounded by the dilatation balloon, is transparent, and index markers are provided along the balloon. Thus, objects against which the balloon wall is pressed when the balloon is inflated can be quantified. This structure requires viewing the lumen through the catheter wall and the balloon wall, and does not address the need for monitoring the position of a prosthesis with respect to its delivery device during deployment. This need is particularly apparent in connection with radially self-expanding prostheses, which are constrained in radially reduced configurations during delivery, and must be released from their confining devices during deployment to permit radial self-expansion.
Therefore, it is an object of the present invention to provide a prosthesis delivery and deployment device that substantially surrounds a prosthesis to retain the prosthesis during delivery to a treatment site, yet facilitates an optical viewing of the prosthesis before and during its deployment.
Another object is to provide a prosthesis delivery device particularly well suited to negotiate tortuous intraluminal pathways in the body that incorporates a translucent carrier segment through which a prosthesis carried within the device can be optically viewed.
A further object is to provide a process for deploying a radially self-expanding prosthesis within a body lumen in which an optical viewing device is advantageously used to view at least a proximal portion of the prosthesis to visually monitor a location of the prosthesis during its deployment.
Yet another object is to provide a catheter or other device for intraluminal delivery of a prosthesis, that incorporates a prosthesis confining wall sufficiently light transmissive to enable a viewing of the prosthesis through the wall, so that an optical instrument positioned within a body lumen outside the catheter can be used to observe the prosthesis contained in the delivery device, as well as tissue surrounding the delivery device.